Radiator Pressure Cap Description; Operation; Diagnosis And Testing Diagnosis And Testing - Cooling System Pressure Cap Testing - Chrysler PT Cruiser Service & Repair Manual

PT
ENGINE COOLANT THERMOSTAT AND HOUSING (Continued)
Fig. 13 Engine Coolant Thermostat Housing
1 - ENGINE COOLANT THERMOSTAT HOUSING
Fig. 14 Thermostat Orientation
1 - ALIGN AIR BLEED WITH NOTCH IN THERMOSTAT HOUSING
2 - THERMOSTAT SEAL
3 - THERMOSTAT HOUSING
(3) Install thermostat
Torque fasteners to 7 N·m (65 in. lbs.) (Fig. 13).
(4) Connect upper radiator hose and heater hose to
thermostat housing.
(5) Install fasteners securing heater return tube to
engine block and thermostat housing.
(6) Install battery.
(7) Connect positive battery cable.
(8) Connect negative battery cable.
(9) Fill cooling system (Refer to 7 - COOLING/EN-
GINE - STANDARD PROCEDURE).
housing and fasteners.
ENGINE - 1.6L SOHC
RADIATOR PRESSURE CAP
DESCRIPTION
The cooling system is equipped with a pressure cap
that releases built up pressure, maintaining a range
of 97-124 kPa (14-18 psi).
There is also a vent valve in the center of the cap.
This valve also opens when coolant is cooling and
contracting, allowing coolant to return to radiator
from coolant recovery container by vacuum through
connecting hose. If valve is stuck shut, the radia-
tor hoses will be collapsed on cool down. Clean
the vent valve (Fig. 15) to ensure proper sealing
when boiling point is reached.
Fig. 15 Cooling System Pressure Cap
1 - OVERFLOW NIPPLE
2 - MAIN SPRING
3 - GASKET RETAINER
4 - STAINLESS-STEEL SWIVEL TOP
5 - RUBBER SEALS
6 - VENT VALVE
7 - RADIATOR
8 - FILLER NECK

OPERATION

The pressure cap allows the cooling system to oper-
ate at higher than atmospheric pressure. The higher
pressure raises the coolant boiling point; this allows
increased radiator cooling capacity.
The gasket in the cap seals the filler neck, so that
vacuum can be maintained, allowing coolant to be
drawn back into the radiator from the reserve container.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - COOLING SYSTEM
PRESSURE CAP TESTING
Dip the pressure cap in water. Clean any deposits
off the vent valve or its seat and apply cap to end of
the Pressure Cap Test Adaptor that is included with
the Cooling System Tester 7700. Working the
plunger, bring the pressure to 104 kPa (15 psi) on the
gauge. If the pressure cap fails to hold pressure of at
least 97 kPa (14 psi), replace the pressure cap.
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